1. Field of the Invention
The present invention relates to a neutral beam source having an electromagnet, and more particularly to a neutral beam source having an electromagnet used for etching a semiconductor device and capable of obtaining a great amount of ion flux at low energy by improving a structure of a plasma chamber of a conventional neutral beam source converting ion beams into neutral beams.
2. Description of the Prior Art
As generally known in the art, an ion beam source is used in various technical fields requiring a uniform beam distribution over a large area. Particularly, such an ion beam source has been widely used in a semiconductor field, so as to implant impurities into a semiconductor substrate, deposit a predetermined material layer on the semiconductor substrate, or etch a predetermined material layer formed on the semiconductor substrate. Herein, the ion beam source ionizes gas and supplies ionized gas into a required place by accelerating ionized gas extracted from a plasma chamber.
Applicant of the present invention has filed a patent application entitled “Ion beam source capable of improving ion flux” with the Korean intellectual property office, which is now pending with Korean laid-open publication No. 2002-92482.
In the accompanying drawings, FIG. 1 schematically shows a conventional inductively coupled RF (radio frequency) ion source 10′ having a helical RF coil.
Referring to FIG. 1, the inductively coupled RF ion source 10′ includes a plasma chamber 11′ made of quartz. In addition, a gas feeding port 19′ is formed at a top of the plasma chamber 11′ in order to feed reaction gas into the plasma chamber 11′. An RF coil 14′ is wound around the plasma chamber 11′. The RF coil 14′ is connected to an RF matchbox 12′, which is connected to an RF power supply 13′ for supplying RF power.
In addition, a dual grid assembly 15′ having a plurality of ion beam paths is provided at a bottom of the inductively coupled RF ion source 10′ in order to control ions extracted from the plasma chamber 11′.
However, a great amount of ions may exist in an etching device using the ion beam source for performing an etching process and such ions may collide with a semiconductor substrate or material layers formed on the semiconductor substrate with hundreds of eV energy, thereby causing electrical damage or physical damage to the semiconductor substrate or the material layers formed on the semiconductor substrate.
To solve the above problem, applicant of the present invention has filed a patent application entitled “Neutral beam etching device” with the Korean intellectual property office, which is now allowed to applicant of the present invention with Korean Patent No. 10-412953.
The neutral beam etching device disclosed in the above patent includes an ion source having a plasma chamber for extracting ion beams, a dual grid assembly positioned at a bottom of the ion source, and a reflective member positioned at a lower end of the dual grid assembly.
However, the above neutral beam etching device must increase voltage applied to the grids in order to increase an amount of ions flux for improving etching performance. That is, in order to increase an acceleration degree and a flow rate of ions passing through the grid assembly, the above neutral beam etching device must apply high voltage to the grids so that ion energy is also increased. However, if the ion energy is increased, kinetic energy of ions is also increased, so a semiconductor substrate may be damaged due to the ions making contact with the semiconductor substrate while an etching process is being carried out.